Evidence Light Travels as a Wave

I go to St Olaves and our science teacher said that light travels in straight line and your website said that it was in waves do you have any evidence so I can debate with my teacher? (please reply quickly please)
- Rickey (age 12)
Britain

There are some simple experiments you can do to show the wave interference properties of light. You can see a picture of some results here: http://en.wikipedia.org/wiki/Double-slit_experiment. (You can ignore the fancy quantum part of that link.)

I think you can directly demonstrate the wave interference patterns, not just show other people's pictures. Try poking very small pin holes very close by each other in a piece of foil, then shine a laser pointer at the holes. View the pattern on a wall a few meters beyond the foil in a dark room. You'll need to mount all the parts, maybe just with some tape in a shoe box, since they'll wobble too much if you hold them.

I wouldn't be surprised if your teacher is aware of these wave effects. If you look at the laser beam itself, say in a slightly dusty room, it looks very close to just traveling in a straight line. For some purposes, that's not a bad approximation.

Mike W.

(published on 09/06/2011)